This invention relates to the use of oxidized polyamines, and especially aminoaldehydes such as NN'- Bis-(3-propionaldehyde)-1-4-diaminobutane (spermine bisaldehyde) both in vitro and in vivo to elicit an immunosuppressive response in living cells. It also relates to the therapeutic application of these compounds to induce an immunosuppressive response in a living organism.